Ten years ago, Citeseer had a feature for finding criticism that google scholar still lacks (AFAIK): if you search for papers citing a particular paper, the excerpt it would show would be where the actual citation occurred, so that you could tell if it was positive or negative. Unfortunately, citeseer seems to have been abandoned years before the launch of google scholar and was inferior in every other way upon that launch.
Ten years ago, Citeseer had a feature for finding criticism that google scholar still lacks (AFAIK): if you search for papers citing a particular paper, the excerpt it would show would be where the actual citation occurred, so that you could tell if it was positive or negative. Unfortunately, citeseer seems to have been abandoned years before the launch of google scholar and was inferior in every other way upon that launch.